On defense, the 49ers’ front seven, with linebackers Aldon Smith (league-leading 19.5 sacks), Patrick Willis (140 tackles), NaVorro Bowman (150 tackles), and Ahmad Brooks (40 pressures) and end Justin Smith (52 quarterback hits, 77 pressures), is arguably the best in football — though the Patriots probably will be out to show the country that theirs is.

As with most of these huge showdowns, the game likely will be decided by the quarterbacks. Tom Brady of the Patriots will put his MVP credentials on display again, against second-year quarterback Colin Kaepernick. He is making his fifth start after replacing veteran Alex Smith, who lost his job after suffering a concussion.

Kaepernick (6 feet 3 inches, 230 pounds) is lanky and a very good athlete. He’s a dual threat throwing (67.4 completion percentage) and running (7.6-yard average, five touchdowns including a 50-yarder in last week’s win over the Dolphins). But he’s never been in a game this big, and his play from the pocket has trended downward since a terrific first start in a 32-7 victory over the Bears Nov. 19. Expect the Patriots to make Kaepernick beat them from the pocket to emerge with a victory.

It all starts up front with an offensive line that is big and strong. From left to right: Joe Staley (6-5, 315), Mike Iupati (6-5, 331), Jonathan Goodwin (6-3, 318), Alex Boone (6-8, 300), and Anthony Davis (6-5, 323). They’re all good, especially in the run game, with Boone and Davis the most susceptible to giving up pressure against the pass. The line paves the way for the explosive running attack of Frank Gore, and rookie speedster LaMichael James. Gore, who is powerful and surprisingly agile, was terrific against a very good Dolphins defense. Michael Crabtree is rounding in the all-around receiver the 49ers were hoping for. Former Giants receiver Mario Manningham (shoulder) missed the Dolphins game but could return against the Patriots. He has an obvious connection with Kaepernick. Randy Moss gets about 22 snaps a game, and rookie A.J. Jenkins has started to get into the mix. Tight end Vernon Davis is still one of the league’s best, and Delanie Walker is versatile. The 49ers use a ton of personnel packages and formations — the Patriots will see various versions of the pistol formation and read option game. The Rams, whom the Patriots trounced but are 1-0-1 vs. the 49ers this season, played all zone against them two weeks ago.

Defense

The front seven is terrific, fast, and physical. End Ray McDonald and nose tackle Isaac Sopoaga are the other starters up front and hold their own. The Smith duo run perhaps the best stunts in the league, so the left side of the Patriots’ line will need to have their communication perfect on Sunday night. The secondary can be had. Safeties Donte Whitner and Dashon Goldson get to the ball but can be boom or bust. Same goes for cornerbacks Carlos Rogers (left) and Tarell Brown (right). Rogers kicks inside in the nickel package and the capable Chris Culliver takes over at left cornerback.

Special teams

Punter Andy Lee is the league’s best. Kicker David Akers has struggled this year over 40 yards (7 of 15). James (kickoffs) and Ted Ginn Jr. are very explosive in the return game.